1. Field of the Invention
This invention relates to water-release transfers. The characteristic of such transfers is that a transferable design layer is released from the water-release layer of a supporting sheet by the application of water which softens the release layer and allows the design layer to be removed from the support and transferred to a receiving surface.
2. Description of the Prior Art
There are two distinct types of such transfers which are termed herein water-slide and reverse-fixing transfers. Water-slide transfers consist of a design layer printed positive onto the water-release layer of the support sheet which is usually a water permeable paper sheet. The transfers are applied by immersion in water and sliding off the released design layer onto the receiving surface, where it is adhered thereto by the material of the release-layer.
Reverse-fixing transfers are printed negative, i.e. in reverse, on the water-release layer of the support substrate and the fixing adhesive is applied as a layer over the design layer or as a layer on the receiving surface. The transfer sheet is applied design side down onto the receiving surface to produce adhesive bonding and the support substrate released and removed by applying water.
Water-release transfers of the prior art have relied on two types of ink to print the design layer, one drying mainly by oxidation and the other exclusively by evaporation. Due to the moisture sensitive nature of the water-release layer on the transfer paper, which is an indispensable component of the system, drying of both the above types of ink must be carried out at room temperature and controlled relative humidity otherwise the transfer paper curls severely and shrinks if subjected to heat in the drying process or a substantial reduction in relative humidity. Consequently it is essential to aircondition the entire plant producing water-release transfers to this humidity to maintain sheet dimensions.
Although water release transfers are widely known and have been used for many years for the decoration labelling and marking of all types of equipment and components many of these applications have declined due to the above problems and the high cost of production.
A further problem which occurs with water release transfers, particularly the water-slide type, is due to the requirement that all the transfer design elements must be tied together by an overall transfer layer having sufficient film strength to avoid fracture or distortion during transfer so that all the design elements are transferred together in the same spatial relationship in which they were printed. This has been achieved by printing an overall clear, white or other coloured transfer layer having the necessary film strength which holds together all the overprinted design elements.
Such a transfer layer necessarily must have a substantial dry film thickness, usually 8-50 micrometers to provide the necessary film strength and flexibility and this requirement implies a correspondingly thick wet film and even longer drying times.